Grease a 13 X 9-inch baking dish with butter or non-stick spray
Tear bagels into bite-sized pieces, and place in baking dish
Place cubes of cream cheese evenly in bagels, and press slightly so they're not just sitting on top
Place blueberries evenly in baking dish, making sure they are evenly distributed throughout the casserole
In a medium mixing bowl, whisk together eggs and heavy cream, then stir in lemon juice and zest
Pour egg mixture over bagel mixture, and press bagels into liquid so that they are completely coated
Cover with plastic wrap, and refrigerate overnight
The next morning, remove from refrigerator, uncover and preheat oven to 350℉
Bake in preheated for 45 minutes, or until casserole is bubbly and center is firm. Toothpick inserted into center should come out mostly clean, and internal temperature should be over ℉ 160
Remove from oven, and allow to rest for 5-10 minutes. Drizzle with lemon glaze if desired. Cut into squares, and enjoy!